The present invention concerns acid catalyzed hydrocarbon conversion processes, and, more particular, recovery of valuable acid catalysts from a product stream leaving a hydrocarbon conversion process.
Acid catalyzed processes are most usually employed in the industrial isomerization and hydration of hydrocarbons and during the preparation of high octane gasoline products by alkylation of paraffinic hydrocarbons.
In those processes, a strong acidic compound is conventionally mixed with a hydrocarbon feedstock in a reaction vessel and agitated for a sufficient time until the desired reaction is completed. The final product containing, furthermore, the acid catalyst is then recovered from the reactor effluent by extraction or distillation.
Acid catalysts most usually employed in the above processes are sulphuric acid and hydrogen fluoride. Other acidic compounds suitable as catalysts in hydrocarbon conversion processes are the strong fluorinated sulphuric or sulphonic acids.
Alkylation of paraffins with olefins in the presence of a fluorinated sulphonic acid catalyst supported on polar contact material is mentioned in EP 433,954. The acid catalyst is by the process of EP 433,954 recovered from an alkylate product stream by extraction with water and distillation of the extracted catalyst.
Removal of sulphonic or sulphuric acid catalyst from a reaction mixture by contacting the mixture with hydrotalcite is disclosed by GB 1,570,932. Hydrotalcite is, thereby, added in form of a powder or as particles to the reaction mixture and the mixture agitated until almost all acidic substances from the mixture are transferred into hydrotalcite and removed by reaction with hydrotalcite. After the reaction, hydrotalcite is separated from the mixture by filtration to obtain a neutral solution.
The above reference is completely silent on recovery of acid catalyst after reaction with hydrotalcite.
In many acid catalyzed processes, it is, however, desirable to recover and reuse the recovered acid catalyst in the processes to improve-process economy and diminish environmental risk during storage and final processing of spent catalyst.
It is thus the general object of this invention to provide a method for the recovery of acid catalyst from a product stream leaving acid catalyzed processes, by which method the removed catalyst is recovered and recycled to the process without further processing of the recovered catalyst.